public class Solution3 {
    //206. 反转链表
    public ListNode reverseList(ListNode head) {
        if (head == null || head.next == null) {
            return head;
        }
        ListNode newHead =  reverseList(head.next);
        head.next.next = head;
        head.next = null;


        return newHead;
    }
}
